Producing isoprene.



IITED STATES PATENT OFFICE.

FRANZ WEBEL, OF MANNHEIM, GERMANY, ASSIGNOR 'IO BADISCHE ANILIN SODAFABRIK, OF LUDWIGSHAFEN-ON-THE-RHINE, GERMANY, A CORPORATION.

rnonncmc ISOPRENE.

No Drawing.

To all 'U]! am. it may concern. 1

lie 1t known that l, FRANZ VVEBEL, citizen ot the German Empire,residing at Mannheim. Germany, have invented new and useful Improvementsin Producing Isoprene, of which the following is a specification.

I have found that I can obtain isoprene by treating methyl-butenolesters at a raised temperature and in the vaporized state with a reagentwhich will catalytically split ofi acid, such for instance as alumina,which is particularly useful, and also barium chlorid and nickelchlorid. It is advantageous to carry out the reaction under reducedpressure.

ethyl butenol esters suitable for employment according to this inventioncan be obtained by-react'ing with a salt of an organic acid ondimethyl-monohalogen-ethyl-halogen-methane as described in theapplication for patentSerial No. 751,105.

The following example will serve to illustrate further the nature ofthis invention 1nd how it can be carried into practical ettect, but myinvention is not confined to this Example. Pass vaporized methyl-butenolwet-ate (for instance the crude product obainable fromtrimet-hyl-ethylene bromid and eodium acetate according to Example 1 ofhe specification of application for patent Serial No. 751,105) overalumina at a temierature of 400 C. and a pressure of about millimeters.Pass the vapors leaving the :ontact space through a condenser, in whichhe main quantity of the acetic acid proluced is condensed, then througha washottle containing alkaline liquor in order to rec the gascompletely from acid, and then ondense the isoprene vapors in apparatusooled to, say 80 C. In this way a good 'ield of very pure isoprene isobtained.

If desired, the process may be carried out Specification of LettersPatent.

under atmospheric pressure, although the yield is then generally notquite so good. Further, instead of methyl-bntenol-acetate, other esterscan be einployed,-in particular other fatty acid esters ofmethyl-butenol.

The temperature at which the process of my invention can be carried outmay be varied within wide limits.

Now what I claim is 1. The process of producing isoprene by treating amethyhbutenol ester at a raised temperature and in the vaporized statewith a reagent which will catalytically split ofl ac1 2. The process ofproducing isoprene by treating a methyl-butenol ester at a raisedtemperature and in the vaporized state with a reagent which willcatalytically split ofi' acid, while employing reduced pressure.

3. The process of producing isoprene by treating a methyl-butenol esterat a raised temperature and in the vaporized state with alumina.

4:. The process of producing isoprene' by treating a methyl-butenolester at a raised temperature and in the vaporized state with alumina,While employing reduced pressure.

The process of producing isoprene by treating methyl-butenol acetate ata raised temperature and in the vaporized state with alumina.

6. The process of producing isoprene by treating methyl-butenol acetateat a raised temperature and in the vaporized state with alumina, whileemploying reduced pressure.

In testimony whereof I have hereunto set my hand in the presence of twosubscribing witnesses.

FRANZ TEBEL. \Vit-nesses:

. Josnrn HEIFFER,

J. ALEC. LLOYD.

Patented J une 2, 1914. Application filed February 27, 1913. Serial No.751,106.

